Almidones

JFS

E: Food Engineering and Physical Properties

Film-forming Characteristics of Starches
Z. LIU AND J.H. HAN ABSTRACT Our objective CT: film-forming character acteristics amylose, ABSTRACT:Our objective was to understand the film-forming characteristics of amylose, amylopectin, and high-amylose (55%) starch solutions at ambient environment. By using an inverted phase-contrast microscopeconnected to an imaging system, we were able to record and analyze the microstructural evolution of starch throughout the process of film formation. The results of image analysis suggested that thecoil-to-helix transition, followed by the helices aggregation, dominated the initial stage of starch film formation from solutions, although the time when these phenomena occurred depended on the amylosecontent. Fresh amylose films exhibited an assembly of giant dendrites with quarternary branches. In contrast, amylopectin films showed a structur ucture networked clusters. Interestingly,nterestingly starch show heterogeneous structure of networked clusters. Interestingly, the high-amylose (55%) starch film show ed a heterogeneous structure with both amylose-rich and amylopectin-rich phases,which are integrated seamlessly by the intermolecular interaction between amylose and amylopectin. Keywords: starch, edible films, image processing, amylose, amylopectin

Introduction
dible filmzs andcoatings based on biopolymers have long been used for protecting foods and pharmaceuticals from moisture and oxygen invasion, as well as for carrying colorants and antimicrobial, flavoring, andleavening agents (Guilbert and others 1995). As a renewable biopolymer that has been massively produced worldwide (Liu 2002), starch is a relatively cost-effective choice compared with protein and wax asthe foundation material for edible films and coatings (Wolff and others 1951; Mark and others 1966; Jokay and Mitan 1969). Furthermore, it is hihghly likely to customize starch-based edible films and...